Abstract
We discuss three general problems concerning the cohomology of a (real or complex) nilpotent Lie algebra: first of all, determining the Betti numbers exactly; second, determining the distribution these Betti numbers follow; and finally, estimating the size of the individual cohomology spaces or the total cohomology space. We show how spectral sequence arguments can contribute to a solution in a concrete setting. For one-dimensional extensions of a Heisenberg algebra, we determine the Betti numbers exactly. We then show that some families in this class have a M-shaped Betti number distribution, and construct the first examples with an even more exotic Betti number distribution. Finally, we discuss the construction of (co)homology classes for split metabelian Lie algebras, thus proving the Toral Rank Conjecture for this class of algebras.
Similar content being viewed by others
References
Armstrong G. (1997). Unimodal Betti numbers for a class of nilpotent Lie algebras. Comm. Algebra 25(6): 1893–1915
Armstrong G., Cairns G. and Jessup B. (1997). Explicit Betti numbers for a family of nilpotent Lie algebras, Proc. Amer. Math. Soc. 125(2): 381–385
Armstrong G. and Sigg S. (1996). On the cohomology of a particular class of nilpotent Lie algebras. Bull. Austral. Math. Soc. 54: 517–527
Cairns G. and Jessup B. (1997). New bounds on the Betti numbers of nilpotent Lie algebras. Comm. Algebra 25: 415–430
Deninger C. and Singhof W. (1988). On the cohomology of nilpotent Lie algebras. Bull. Soc. Math. France 116: 3–14
Dixmier J. (1955). Cohomologie des algèbres de Lie nilpotentes. Acta Sci. Math. 16: 246–250
Halperin S.: Rational homotopy and torus action, In: Aspects of Topology. London Math. Soc. Lecture Notes, Ser. 93, Cambridge University Press, Cambridge, 1985, pp. 293–306.
Pouseele H. On the cohomology of extensions by a Heisenberg Lie algebra, to appear in: Bull. Austral. Math. Soc.
Pouseele, H. and Tirao, P.: Constructing Lie algebra homology, to appear in: J. Algebra.
Santharoubane L.J. (1983). Cohomology of Heisenberg Lie algebras. Proc. Amer. Math. Soc. 87(1): 23–28
Tirao P. (2000). A refinement of the Toral Rank Conjecture for 2-step nilpotent Lie algebras. Proc. Amer. Math. Soc. 185(10): 2875–2878
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Pouseele, H. Betti Number Behavior for Nilpotent Lie Algebras. Geom Dedicata 122, 77–88 (2006). https://doi.org/10.1007/s10711-005-9029-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10711-005-9029-9